Double-spring gage.



G. J. MANNING.

DOUBLE SPRING GAGE.

APPLICATION FILED JULY 25, 1913.

Patented June 23, 1914.

fnvenion' I 7 Cole maul Mann/i73 "UNITED STATES PATENT OFFICE.

COLEMAN J'. MANNING, OF MEIDFOR-D, MASSACHUSETTS, ASSIGNOR TO AMERICANSTEAM GAUGE & VALVE MANUFACTURING CO., OF BOSTON, MASSACHUSETTS, A

CORPORATION OF MASSACHUSETTS.

DOUBLE-SPRING GAGE.

Specification of Letters Patent. Patented J 11119 23 1914.

Application filed July 25, 1913. Serial No. 781,118.

This invention relates to gages of the Bourdon type, and particularly togages in which the effects of two Bourdon spring tubes are compounded toactuate a single indicator or recorder, such as, for instance, apointer, a hand or a marker, arranged to travel over a dial.

The objects of the invention are, mainly, to furnish a simple mechanismfor transmitting the motion of the spring tubes to the indicatingelement, of which the parts may be used interchangeably and withoutspecial fitting, not only in all gages of the same size and calibration,but also in gages of widely varying sizes and designed to indicate orrecord widely varying pressures; to make provision for such adjustmentof the transmitting mechanism that spring tubes of the same size andpower may be used 1n lnstruments designed for different pressures; and

to provide an improved movement frame for the gearing which directlyactuates the indicating element.

Heretofore it has been necessary in practice to fit the parts of thetransmitting mechanisms specially for each instrument and to useparticular care in locating the points of connection of such parts witheach other and with the spring tubes, with the result that such partscould be used only in the instrument to which they were fitted and notin any other instrument, and that the manufacture and calibration ofaccurate gages has been a difiicult and expensive matter, and it hasbeen necessary to provide special spring tubes for each class of gage.

It is the purpose of the present invention to enable the parts of thetransmission mechanism to be made in quantities, all duplicates of thesame parts being exactly alike, ready to be assembled correctly andwithout necessity of special fitting or particular care in assembling,in instruments of diverse quallties, and in condition to be calibratedand so made ready for use by a single adjustment; and also to makeunnecessary the provision of spring tubes specially constructed forvarious pressures, by providing for such a range of calibrationadjustment in the transmitting mechanism that the same spring tubes maybe employed in a wide variety of gages designed for different pressures.

In the drawings forming a part of this application, Figure 1 representsan elevation of the preferred embodiment of my invention, represented asassembled in operative condition in the gage, Fig. 2 is a plan view ofthe apparatus shown in Fig. 1., Fig. 3 is an elevation of the partsshown in the upper portion of Fig. 1, illustrating extreme adjustmentsof the transmission mechanism, Fig. 4 is a side elevation and partialsection on line 1-4 of Fig. 1 of the movement frame which supports thatpart of the trans mission mechanism which is known as the movement.

The same reference characters indicate the same parts in all thefigures.

In the drawings 10 represents a hollow head which is fitted in thecasing of the gage and is adapted to be put into communication with thepressure to be measured. Curved spring tubes 11 and 12 are attached toopposite sides of the head in communication with the interior thereofand extend oppositely therefrom, being at opposite sides of the gage andcurved about substantially the same center. These spring tubes are ofthe common Bourdon type, which are commonly known in the art as springs.The ends of the spring tubes are closed and have projecting lugs orfingers 13 and 141, respectively, for connection with the transmittingmechanism.

The transmitting mechanism consists of a bell crank lever 15 pivoted bymeans of a stud 16 to the projection or lug 141 of the spring tube 12, alink 17 pivoted by a stud 18 to the lug or finger 18 of spring tube 11,an intermediate link 19 pivoted at 20 to one arm of the bell crank lever15 and at 21 to the link 17, and a link 22 which connects the bell cranklever 15 with the gearing known in.the art as the movement of the gagewhich consists of a gear segment 23 and a pinion 24 which meshes withthe teeth of the segment 23 and is fixed upon a shaft or spindle 25which carries the indicating or recording element. A coiled spring 26 isprovided as usual to return the indicator to zero position when thespring tubes are relaxed, that is, not distorted by a difference betweeninternal and external pressures.

The present invention relates particularly to that part of thetransmitting mechanism which consists of the lever 15 and links 17 and19. These members or parts are freely connected pivotally with thespring tubes and with each other by means of the studs 16, 18, 20, and21, which studs may have cylindrical. shanks fitting freely in the holesprovided for them in the above described parts and shouldered threadedends for attachment to the parts in which they are movably mounted. Ineach case the distance between the shoulder adjacent to the threaded endand the head of the stud may be slightly greater than the thickness ofthe part which receives the smooth shank of the stud so that thepivotally mounted part will not be bound by the head of the stud. Thestud 20 is rigidly mounted in this manner on the end of the bell cranklever 15 and the stud 21 is rigidly mounted in the end of the link 17,the intermediate link 19 being pivoted freely at its opposite ends onthese studs. The link 19 may be prevented from swinging upon the pivotstud 20 by means of a clamp screw 27 which passage through a slot 28 ina widened part of the link 19 and is threaded into the lever 15, beingadapted to bind the link 19 against the adjacent arm of the lever 15 bymeans of its head. When clamped in this manner the link 19 becomes ineffect a rigid part of the lever 15 so that the distance between thepivot 16 and the connection 21 becomes one of the arms of this lever,the other aim being the one which is connected with the link 22 by thestud 29. By swinging the link 19 about the pivot 20 the distance betweenthe pivots 16 and 21 may be varied,

and then fixed by screwing down the clamp ing screw 27 When the saidscrew is made firm, the link 19 is a rigid part of the lever 15, and thepoint of application of the pull or thrust of link 17 is the pivot 21,which makes the effective lever arm through which the spring tube 11acts 011 the lever 15, the distance between the points 16 and 21. Thisdistance may be increased or diminished and the effectlve lever armtherefore correspondingly altered by raising or lowering the link 19. InFig. 8 the full lines show the uppermost limit of adjustment and thedotted lines the lower limit of adjustment of these parts. The fact thatin these adjustments the links 17 and 19 swing about pivots 1S and 20which are near together enables the adjustment to be made withoutdisplacing the lever 15 to any material extent, that is, to an extentgreat enough to cause any dilliculty in calibrating the gage. It would.be possible to extend the lever 15 far enough to bring the pivot 20substantially coaxial with the pivot 18, and in such case theadjnstments could be made without causing any change whatever in theangular position of lever 15. The proportions illustrated are desirable,however, because they enable the same sized levers 15 and links 19 to beused in gages of widely varying sizes, that is, gages relatively muchsmaller than those shown in these drawings.

The movement of the two spring tubes 11 and 12 under pressure iscompounded by the lever 15 and by the latter applied to the indicator.The amount of movement given to the indicator is determined both by thespring of the tubes and by the movement imparted to the end 29 of thelever thereby. Spring tubes are designed for certain pressures, and aregraded according to the pres sures which cause their free ends to move acertain amount. For instance, tubes are graded as 400 pound springs, 300pound springs, etc., according as their free ends are caused to springapproximately the same amount, which is in the neighborhood of a quarterof an inch by pressures of 400 pounds, 300 pounds, etc.

My invention is of particular importance in that it enables springsgraded alike to be used in gages of different calibration, securing thisresult by the adjustment of the pivot point 21. Evidently when the pivot21 is widely separated from the pivot 16 a certain movement of thespring tubes will not move the pivot 29 and the indicator so far as thesame movement of the tubes when the pivot 21 is nearer to the pivot 16.Thus a spring graded as a 400 pound spring, for instance, may be usednot only in a gage rated as a 4-00 pound gage, but also in a wide rangeof gages having higher or lower ratings, the use being made possiblewith exact calibration and perfect accuracy by the adjustment providedfor the pivot 21. By this means the manufacturer is relieved of thenecessity of keeping large numbers of so many grades of spring tube instock as he would be required to do if a spring of a certain grade onlycould be used in gages of a particular rating.

Another advantage of the improved mech anism is that the parts may beproduced in large quantities, by economical methods of manufacture, withtheir pivot holes bored and located by jigs or other fixed standards andthat the parts so produced may be used interchangeably for one anotherfor all the gages of a wide range. So far as I am aware this is anadvantage never secured by any mechanism heretofore produced, and it iscertainly not obtainable by the Practical methods in present use.According to the practised methods, the parts for each individual gage,or each type of gage requlre special fitting in some particulars. In mydevice each of the members is in one piece and is neither extensible norotherwise adjustable. Only one adjustment is provided or is necessary,and this adjustment is sufiicient to effect proper calibration of gageswithin wide limits of rating.

A further improvement resides in the frame which supports the indicatormovement. This frame consists of a plate 30 having posts 31 and 32 towhich is secured an upper plate 33, the said plates 30 and 33 containingbearings for the element 25 and for the arbor 24 of the segment 23. Thebottom plate 30 is secured to the back-wall of the gage by screws 35 andthe top plate 33 is secured to the posts by screws 36. Here toforemovement frames of gages have been provided with posts which arestructurally independent and separate from both plates, and this hasgiven trouble, particularly in locomotive gages and other gagessubjected to jarring, by reason of the tendency of the posts to becomeloose. By this improvement the posts 31 and 32 are made integral withthe bottom plate 30, as appears from Fig. 4, being formed as a part ofthe same casting or forging. No amount of jarring can possibly loosenthese integral posts from the bottom plate, and the movement frame isthus more rigid and secure than any heretofore made.

I do not limit the invention to gages in which the pressures dealt withare greater than atmospheric, since the same principles could beemployed in a vacuum gage as well. Neither do I desire in all respectsto limit the invention to a double spring gage, that is, to one havingtwo spring tubes, nor to a gage in which the pressure-operated membersare actually curved spring tubes rather than elements or members havingother shapes. As a matter of general statement it may be considered thatthe fingers 13 and 14 are abutments for the lever 15 and the link 17,respectively, either or both of which may be movable and either of whichmight be stationary, when applied to certain conditions; and that theadjustable links 19 and 17 provide means for connecting the lever withthe abutment 13 and for adjusting the length of that arm of the leverwhich is connected to said abutment.

What I claim and desire to secure by Letters Patent is 1. In a gage forindicating pressure differences, the combination of two members, one ofwhich is relatively movable with respect to the other, and one of whichis a pressure actuated member, while the other is an abutment, a leverpivotally mounted on one of said members, a link pivoted to the other ofsaid members, an intermediate link pivotally connected with both saidlever and said first-named link, means for rigidly clamping saidintermediate link to the lever in various positions angularly about itspoint of connection with the lever, an indicator, and means fortransmitting motion from said lever to said indicator.

2. In a pressure gage the combination,-

with a pressure actuated member, of a transmitting mechanism consistingof a lever, an abutment, a link pivoted to said abutment, and anintermediate link connected both with said lever and the first namedlink, its point of connection with the lever being between andsubstantially in line with the ends of the first named link, saidintermediate link being adjustable about its point of connection withthe lever, and means for securing said link in its adjustments.

3. A motion-transmitting mechanism for pressure gages comprising aspring tube, an abutment, a lever pivoted to said tube and having an armextending toward said abutment, a link pivoted to said arm at a pointnear the abutment and extending away from the abutment and a second linkpivoted to the abutment and extending approximately parallel to thefirst link and pivoted to the latter, said first named link having atransverse slot, and means mounted on said lever arm and passing throughsaid slot for clamping said link in various positions of angularadjustment to said arm.

4. In a pressure gage the combination of a pressure actuated member, anindicator and a motion transmitting mechanism, consisting of anabutment, a lever pivoted to said pressure actuated member and having aconnection at one end for applying motion to said indicator, a linkpivoted to said abutment, a link pivoted to said lever and also to saidfirst named link, said pivotpoints being all approximately in line andthe pivot between the lever and second link being intermediate the pivotpoints of the first link, and the pivot point between the two linksbeing approximately in line with the fulcrum of the lever and itsconnection with the indicator operating connections.

5. In a pressure gage the combination of a pressure-operated member andan abut spect to the lever, and means for securing 1o inent, a leverpivoted to said abutment, a the adjustments of said connection.

link pivoted to said pressure-0perated1ne111- In testimony whereof Ihave ailixed my ber, an intermediate element connecting said signature,in presence of two witnesses.

' link and lever and so arran 'ed that its Joint T i of connection Withthe leve i is bGtWGGli and COLEMAN MANNIA (L approximately in line Withthe ends of the Witnesses: link in all positions, said intermediate conE. P. BRANNEN, nection being adjustable angularly With re- P. lV.PEZZETTI.

Copies 01 this patent may be obtained for five cents each, by addressingthe Commissioner of E'atents. Washington, I). G.

It is hereby certified that in Letters Patent No. 1,100,756, grantedJune 23, 1914:,

upon the application of Coleman J. Manning, of Medford, Massachusetts,for an improvement in Double-Spring Gages, an error appears in theprinted specification requiring correction as follows: Page 2, line 41,for the word passage read passes; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Ofiice.

Signed and sealed this 7th day of July, A. D., 1914.

i R. F. WHITEHEAD,

Acting Commissioner of Patents.

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